[Unnecessary operations in shoulder surgery: "table of confusion" applied to "field of confusion"].

Attributing a surgical procedure as unnecessary or necessary is a binomial classifier that can be analysed in a so called "table of confusion". Ambroise Parré (1510 - 1590) observed that wound treatment with hot oil was harming instead of healing, and concluded that it should be discarded as "standard of care". Still today, the answer to the same question "What is the standard of care?" is decisive when an operation needs to be classified as "necessary" or "unnecessary". Patients' expectations can also influence the decision making process between surgical and conservative treatment options. Fracture of the humeral head is an example how two different surgical strategies (primary versus secondary joint replacement) can lead to "unnecessary" operation. However, it is only retrospectively that an operation appears unnecessary. Further factors that could be analysed are the delay between decision and operation (so called "test of time") and financial aspects. In conclusion, it is only objective and scientific analysis that can lead to viable standards of care for our practice. This is the only way to protect patients as well as surgeons from unnecessary operations.